1. Field of the Invention
The invention relates to an MR device for determining the nuclear magnetization distribution in an examination zone by means of a cylindrical surface coil system which includes at least two coils which are constructed as respective loops. The invention also relates to a head coil system with a surface coil system which includes at least two coils which are constructed as respective loops.
2. Description of Related Art
The determination of the nuclear magnetization distribution in an examination zone by means of a surface coil system consisting of at least two surface coils offers the advantage that the signal-to-noise ratio is significantly enhanced in comparison with coils receiving spin resonance signals from the entire examination zone. A surface coil 10 system is known from Magnetic Resonance in Medicine 16, pp. 192-225, 1990. Therein, the images of the individual surface coils are combined so as to form an overall image by means of an appropriate method. It is a drawback of a surface coil system that its sensitivity is locally not uniform, i.e. that it is dependent on where in the examination zone the MR signal occurs.
A head coil system is known from 2nd SMR, Book of Abstracts, page 1103, 1994. Therein, a coil system which consists of six elements and can be wrapped around the head is supplemented by a butterfly coil which consists of two elements and is arranged on the skullcap of the patient. It is thus achieved that MR signals are also received from the area of the top of the head, but the sensitivity of the two butterfly elements is not very uniform so that problems are encountered when the individual images are combined so as to form an overall image. Moreover, two further receiving channels are required for the two butterfly elements.